The invention relates to an arrangement for the handling of photographic films, particularly sheet-like films provided with means for sensing the travel of the film through the arrangement, in particular for the purpose of controlling the operation of a regeneration arrangement.
Arrangements of this type having at least one pair of cooperating transport rollers are known. For the sensing of the passage of the film through the arrangement, there are provided detector switches comprised of sensing levers which move between a rest position, in which they rest in a recess in a counter pressure surface, and a work position, in which they ride on the surface of the travelling film. For films of relatively low sensitivity, such film detector devices can be satisfactorily employed. However, for some types of film, for example very-high-sensitivity X-ray films provided with photosensitive material on both film faces, the film exposure resulting from the applied pressure and the damage to the film surface are not acceptable.
It is also known to monitor the travel of the film through the film-processing arrangement indirectly through the use of very finely adjusted means operative for detecting the relative movements of pairs of transport rollers in the arrangement during the film travel. However, this expedient is very expensive.
Finally, it has been proposed to make use of sensors which are laterally displaceable out of the path of movement of the travelling film, so that these sensors would engage only the lateral edges of the travelling film. These sensing devices have the disadvantage that the film to be transported must be carefully positioned along one of the sides of the film guide track, in order to assure a reliable activation of the sensing device. Accordingly, there exists with such devices a considerable possibility of malfunction due to errors on the part of operating personnel, i.e., when the film is not precisely enough guided along the side of the guide track.